a Whole Genome Array Approach - Jacobs University

Results and Discussion
sulphatase genes without specificity (RB3956, RB5294), and one alkylsulfatase (RB11502)
within the different stress experiments. Furthermore, during life cycle experiments
(unpublished data) we found evidence that certain sulfatases are only regulated in specific
growth stages which indicates their involvement in the remodeling of the distinct
morphological features of R. baltica. RB1477, RB5294, RB9498 and RB11502 were
induced. We propose a RB9498 and RB11502 have an extracellular function and may be
involved in the formation of a protective substance.
Six sulfatase genes (RB406, RB684, RB1205, RB3403, RB5146 and RB13145) were
repressed after 300 min of heat shock. They could have been involved in the rearrangement
of the cell wall formation, which consists of a protein sacculus with disulfide bonds [12]. In
summary, these results show again how diverse the role of the sulfatases might be and that
only a variety of different experiments will lead to more knowledge on the sulfatases.
Conclusion
This work presents the first transcriptome study of the environmental stress response of a
marine, free-living Planctomycete. Although R. baltica is an unusual organism in many
aspects, the stress responses to heat and cold shock as well to changing salinity were in line
with earlier results reported for other model organisms. Heat shock induced a set of
chaperons, likely to protect cellular proteins from denaturation and breakdown. Growth in the
cold can be followed by the induction of genes altering lipid metabolism. Salinity shift
resulted in the activation of a planctomycete-specific groups of genes, genes involved in
morphology change and the induction of an extracytoplasmatic stress response. All stressors
triggered the down-regulation of the ribosomal machinery, the up-regulation of transposases
to enhance the genetic activity and the induction of several ECF-sigma factors and twocomponent
systems. This confirms the hypothesis that R. baltica is regulating its gene
activity on a global- rather than on the operon level. Besides well characterized stress
response genes about 1000 genes of unknown function, constituting 13 % of the genes
predicted in the genome, were affected. Among them a set of genes most likely involved in
global regulation could be proposed. This in combination with proteome studies and the
presence of some of the genes in fosmid libraries confirmed the essential role of the vast
amount of genes with so far unknown functions in the adaptation of environmental organisms
to changing conditions. Noteworthy is the regulation of 11 sulfatases during stressful
conditions, which indicates that these genes are heavily involved in the core functions
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